Microstructure and indentation mechanical properties of YSZ nanostructured coatings obtained by suspension plasma spraying

[EN] A commercial nanosuspension of yttria-stabilised zirconia (YSZ) was successfully deposited on austenitic stainless steel substrate by suspension plasma spraying technique (SPS). A SG-100 torch with internal radial injection was used for the spraying. The pneumatic system transported the feed suspension from the containers to the plasma torch. In order to study the effect of the spraying parameters, a factorial model was used to design the experiments, changing both spraying translation speed and suspension flow rate. The coating microstructure was characterised by FEG-SEM. All coatings displayed a two-zone microstructure formed by nanometre-sized particles surrounded by fully molten areas. Moreover, crystalline phases were determined by XRD and Raman spectroscopy. Mechanical properties were also determined using nanoindentation technique. Nanoindentation tests showed a bimodal distribution of the mechanical properties (hardness and Young's modulus) which is related to the two zones (molten and partially molten) present in the coatings. (C) 2012 Elsevier B.V. All rights reserved.This work has been supported by the Spanish Ministry of Science and Innovation (project MAT2009-14144-C03) and the Research Promotion Plan of the Universitat Jaume I, action 2.1 (ref. E-2011-05) and action 3.1 (ref. PREDOC/2009/10). The authors are grateful to Leszek Łatka for his help in plasma spray experiments.Carpio, P.; Rayón Encinas, E.; Pawlowski, L.; Cattini, A.; Benavente Martínez, R.; Bannier, E.; Salvador Moya, MD.... (2013). Microstructure and indentation mechanical properties of YSZ nanostructured coatings obtained by suspension plasma spraying. Surface and Coatings Technology. 220:237-243. https://doi.org/10.1016/j.surfcoat.2012.09.047S23724322

Sliding Wear Behavior of Al2O3-TiO2 Coatings Fabricated by the Suspension Plasma Spraying Technique

[EN] The friction and dry sliding wear behavior of alumina and alumina-titania near-nanometric coatings were examined. Coatings were obtained by the suspension plasma spraying technique. Dry sliding wear tests were performed on a ball-on-disk tribometer, with an Al2O3 ball as counterpart material, a normal load of 2 N, a sliding distance of 1200 m and a sliding speed of 0.1 m/s. The effect of including TiO2 in the fabricated coatings on friction coefficient behavior, wear rates and wear damage patterns was determined. The addition of TiO2 to the coatings was found to greatly increase wear resistance by, for example, 2.6-fold for 40 wt% of TiO2. The analysis of the wear surface was correlated with microstructural parameters, mechanical properties and wear rates.The authors wish to thank for the Spanish Ministry of Economy and Competitiveness (MAT2012-38364-C03) and the Autonomous Government of Valencia for funding for the stay in SPCTS-UMR CNRS (France), and the French FCENANOSURF consortium funded by the French Ministry and Industry and local governments of Region Centre and Region Limousin.Klyatskina, E.; Espinosa Fernández, L.; Darut, G.; Segovia López, EF.; Salvador Moya, MD.; Montavon, G.; Agorges, H. (2015). Sliding Wear Behavior of Al2O3-TiO2 Coatings Fabricated by the Suspension Plasma Spraying Technique. Tribology Letters. 59(1):1-9. https://doi.org/10.1007/s11249-015-0530-5S19591Pawlowski, L.: The Science and Engineering of Thermal Spray Coatings. Wiley: Hoboken (2008)Lampe, Th, Eisenberg, S., Cabeo, E.R.: Plasma surface engineering in the automotive industry—trends and future prospective. Surf. Coat. Technol. 174–175, 1–7 (2003)Wang, Y., Jiang, S., Wang, M., Wang, S., Xiao, T.D., Strutt, P.R.: Abrasive wear characteristics of plasma sprayed nanostructured alumina/titania coatings. Wear 237, 176–185 (2000)Kabacoff, L.T.: Nanoceramic coatings exhibit much higher toughness and wear resistance than conventional coatings. AMPITAC Newslett. 6(1), 37–42 (2002)Wang, M., Shaw, L.L.: Effects of the powder manufacturing method on microstructure and wear performance of plasma sprayed alumina–titania coatings. Surf. Coat. Technol. 202, 34–44 (2007)Shaw, L.L., Goberman, D., Ren, R., Gell, M., Jing, S., Wang, Y., Xiao, T.D., Strutt, P.R.: The dependency of microstructure and properties of nanostructured coatings on plasma spray conditions. Surf. Coat. Technol. 130, 1–8 (2000)Dahotre, N.B., Nayak, S.: Nanocoatings for engine application. Surf. Coat. Technol. 194(1), 58–67 (2005)Sathish, S., Geetha, M., Aruna, S.T., Balaji, N., Rajam, K.S., Asokamani, R.: Sliding wear behavior of plasma sprayed nanoceramic coatings for biomedical applications. Wear 271, 934–941 (2011)Pawlowski, L.: Finely grained nanometric and submicrometric coatings by thermal sparing: a review. Surf. Coat. Technol. 202, 4318–4328 (2008)Xiao, D., Wang, Y., Strutt, P.: Fabrication and evaluation of plasma sprayed nanostructured alumina–titania coatings with superior properties. Mater. Sci. Eng. 301, 80–89 (2001)Tjong, S.C., Chen, H.: Nanocrystalline materials and coatings. Mater. Sci. Eng. 45, 1–88 (2004)Fauchais, P., Montavon, G., Bertrand, G.: From powders to thermally sprayed coatings. J. Therm. Spray Technol. 19, 56–80 (2010)Lima, R.S., Marple, B.R.: Thermal spray coatings engineered from nanostructured ceramic agglomerated powders for structural, thermal barrier and biomedical applications: a review. J. Therm. Spray Technol. 16, 40–63 (2007)Fauchais, P., Etchart-Salas, R., Delbos, C., Tognonvi, M., Rat, V., Coudert, J.F., Chartier, T.: Suspension and solution plasma spraying of finely structured layers: potential application to SOFCs. J. Phys. D Appl. Phys. 40, 2394–2406 (2007)Ramachandran, K., Selvajaran, V., Ananthapadmanabhan, P.V., Sreekumar, K.P.: Microstructure, adhesion, micro hardness, abrasive wear resistance and electrical resistivity of the plasma sprayed alumina and alumina–titania coatings. Thin Solid Films 315, 144–152 (1998)Lee, S.W., Morillo, C., Lira-Olivares, J., Kim, S.H., Sekino, T., Niihara, K., Hockey, B.J.: Tribological and microstructural analysis of Al2O3/13TiO2 nanocomposites to use in femoral head of hip replacement. Wear 225, 1040–1044 (2003)Dejang, N., Watcharapasorn, A., Wirojupatump, S., Niranatlumpong, P., Jiansirisomboon, S.: Fabrication and properties of plasma-sprayed Al2O3/TiO2 composite coatings: a role of nano-sized TiO2 addition. Surf. Coat. Technol. 204, 1651–1657 (2010)Yimaz, S.: An evaluation of plasma sprayed coatings based on Al2O3 and Al2O3–13wt% TiO2 with bond coat on pure titanium substrate. Ceram. Int. 35, 2017–2022 (2009)Fervel, V., Normand, B., Coddet, C.: Tribological behavior of plasma sprayed Al2O3-based cermet coatings. Wear 230(1), 70–77 (1999)Vargas, F., Ageorges, H., Fauchais, P., López, M.E.: Mechanical and a tribological performance of Al2O3 coatings elaborated by flame and plasma spraying. Surf. Coat. Technol. 205, 1132–1136 (2010)Bacciochini, A., Ilavsky, J., Montavon, G., Denoirjean, A., Ben-ettouil, F., Valette, S., Fauchais, P., Wittmann-teneze, K.: Quantification of void network architectures of suspension plasma-sprayed (SPS) yttria-stabilized zirconia (YSZ) coatings using ultra-small-angle X-ray scattering (USAXS). Mater. Sci. Eng. 528, 91–102 (2010)ASTM International: ASTM G99-03: Standard test method for wear testing with a pin-on-disc apparatus. ASTM annual book of standards. ASTM International: West Conshohocken (2003)Lancaster, K.: The influence of substrate hardness on the formation and endurance of molybdenum disulphide films. Wear 10, 103–107 (1967)Fauchais, P., Rat, V., Delbos, C., Fazilleau, J., Coudert, J.F., Chartier, T., Bianchi, L.: Understanding of suspension plasma spraying of finely structured coatings for SOFC. IEEE Plasma Sci. 33(2), 920–930 (2005)Bannier, E., Vicent, M., Rayón, E., Benavente, R., Salvador, M.D., Sánchez, E.: Effect of TiO2 addition on the microstructure and nanomechanical properties of Al2O3 suspension plasma sprayed coatings. Appl. Surf. Sci. 316, 141–146 (2014)Darut, G., Klyatskina, E., Valette, S., Carles, P., Denoirjean, A., Montavon, G., Ageorges, H., Segovia, F., Salvador, M.D.: Architecture and phases composition of suspension plasma sprayed alumina–titania sub-micrometer-sized coatings. Mater. Lett. 67, 241–244 (2012)Fauchais, P., Montavon, G.: Latest developments in suspension and liquid precursor thermal spraying. J. Therm. Spray Technol. 19(1–2), 226–239 (2010)Darut, G., Ben-Ettouli, F., Denoirjean, A., Montavon, G., Ageourges, H., Fauchais, P.: Dry sliding behavior of sub-micrometer-sized suspension plasma sprayed ceramic oxide coatings. J. Therm. Spray Technol. 19, 275–285 (2010)Tingaud, O., Bacciochini, A., Montavon, G., Denoirjean, A., Fauchais, P.: Suspension DC plasma spraying of thick finely-structured ceramic coatings: process manufacturing mechanisms. Surf. Coat. Technol. 203, 2157–2161 (2009)Guesama, S., Bounazef, M., Nardin, P., Sahraoui, T.: Wear behavior of alumina–titania coatings: analysis of process and parameters. Ceram. Int. 32, 13–19 (2006)Espinosa-Fernández, L., Borrell, A., Salvador, M.D., Gutierrez-Gonzalez, C.F.: Sliding wear behavior of WC–Co–Cr3C2–VC composites fabricated by conventional and non-conventional techniques. Wear 307, 60–67 (2013)Zhang, J., Moslehy, F.A., Rice, S.L.: A model for friction in quasi-steady-state. Part I. Derivation. Wear 149, 1–12 (1991)Zhang, J., Moslehy, F.A., Rice, S.L.: A model for friction in quasi-steady-state sliding Part II. Numerical results and discussion. Wear 149, 13–25 (1991)Bolelli, G., Cannilo, V., Lusvarghi, L., Manfredini, T.: Wear behaviour of thermally sprayed ceramic oxide coatings. Wear 261, 1298–1315 (2006)Normand, B., Fervel, V., Coddet, C., Nikitine, V.: Tribological properties of plasma sprayed alumina–titania coatings: next term role and control of the microstructure. Surf. Coat. Technol. 123, 278–287 (2000)Hutchings, I.: Tribology: friction and wear of engineering materials. Mater. Des. 13, 187 (1992)Ahn, J., Hwang, B., Song, E.P., Lee, S., Kim, N.J.: Correlation of microstructure and wear resistance of Al2O3–TiO2 coatings plasma sprayed with nanopowders. Metall. Mater. Trans. A 37, 1851–1860 (2006)Erickson, L.C., Hawthorne, H.M., Troczynski, T.: Correlations between microstructural parameters, micromechanical properties and wear resistance of plasma sprayed ceramic coatings. Wear 250, 569–575 (2001)Song, E.P., Ahn, J., Lee, S., Kim, N.J.: Microstructure and wear resistance of nanostructured Al2O3–8 wt%TiO2 coatings plasma-sprayed with nanopowders. Surf. Coat. Technol. 201, 1309–1315 (2006)Tucker Jr., R.C.: ASM Handbook Volume 5A: Thermal Spray Technology. ASM International, Materials Park (2013)Stachowiack, G.W., Batchelor, A.: Engineering Tribology Handbook. Elsevier-Butterworth-Heineman: Oxford (2005)Fischer, T.E., Zhu, Z., Kim, H., Shin, D.S.: Genesis and role of wear debris in sliding wear of ceramics. Wear 245, 53–60 (2000)Lima, R.S., Moureau, C., Marple, B.R.: HVOF-sprayed coatings engineered from mixtures of nanostructured and submicron Al2O3–TiO2 powders: an enhanced wear performance. J. Therm. Spray Technol. 16, 866 (2007

Study of the structure and mechanical properties in 8 mol% yttria-stabilized zirconia coating manufactured by suspension plasma spraying

RESUMEN: El estudio de recubrimientos nanoestructurados fabricados mediante proyección térmica ha generado un gran interés en las últimas dos décadas debido a su considerable mejora en sus propiedades sobre todo en las propiedades físicas y mecánicas. Esta mejora resulta de reducir los tamaños de grano de su materia prima a escalas de 100 a 1000 veces más bajas comparadas con los recubrimientos convencionales microestructurados. Así, estos recubrimientos con estructuras a nivel nano y/o submicrométrica están empezando a ser usados en la industria gracias a sus sobresalientes propiedades y es fundamental el estudio de sus propiedades mecánicas para determinadas aplicaciones. En la actualidad, la indentación es la principal técnica de caracterización de recubrimientos y películas delgadas, a pesar de estar altamente influenciada por los defectos propios del recubrimiento en la vecindad de la indentación. La nanoindentación y la microindentación se presentan como la mejor opción para evaluar el comportamiento mecánico de estos recubrimientos nanoestructurados. Por esta razón, en este trabajo se analizó el efecto de la estructura de un recubrimiento de circona estabilizada con 8% en mol de itria (8YSZ) elaborado por proyección térmica por plasma a partir de suspensiones nanométricas (SPS) y su relación con sus propiedades mecánicas (dureza y módulo de elasticidad) medidas por las técnicas de nanoindentación y microindentación. El análisis de la estructura de la sección transversal mostró que el recubrimiento exhibe una estructura bimodal, la cual está compuesta por una zona con partículas nanométricas semifundidas (ZS) y lamelas con mayor grado de fusión (ZF). Los ensayos de nanoindentación mostraron una distribución de Weibull bimodal de sus propiedades mecánicas, la cual característica de este tipo de recubrimientos; mientras que la dureza (HV) y el módulo de elasticidad evaluados por microindentación, presentaron una distribución monomodal. Estos resultados de microindentación estuvieron influenciados por el área de contacto en las zonas indentadas en la estructura bimodal del recubrimiento. Palabras clave: Recubrimiento por plasma a partir de suspensiones (SPS), estructura, indentación, Distribución Weibull, recubrimiento 8YSZ.ABSTRACT: The study of nanostructured coatings manufactured by thermal spraying has generated a great interest in the last two decades due to their considerable improved properties especially in the physical and mechanical properties. This improvement is to reduce grain sizes of their raw materials at scales of 100-1000 times lower compared to conventional coatings (microstructured). Thus, these coatings structured at the nano and sub micrometric scale start to be used in the industrial applications and, it is essential to study their mechanical properties for certain applications. Currently, the indentation is the main technique for characterizing thin films and coatings, despite being highly influenced by the defects of the coating in the vicinity of the indentation. Nanoindentation and microindentation is presented as the best option for evaluate the mechanical behavior of nanostructured coatings. For this reason, in this work the study of the effect of the structure of the 8 mol% yttria-stabilised zirconia coating (8YSZ) manufactured by suspension plasma spraying (SPS) and the relationship with its mechanical properties (hardness and elastic modulus) measures for nanoindentation and microindentation techniques was analyzed. Analysis of the structure of the cross section of coating exhibit a bimodal structure, which is composed by a zone with semi-molten nanoparticles (ZS) and lamellaes with a higher grade of fusion (ZF). Nanoindentation tests showed a bimodal Weibull distribution of the mechanical properties (hardness and elastic modulus) which is related to the two zones (ZF and ZS) present in the coat-ing, while hardness (HV) and elastic modulus measured by microhardness, showed a monomodal distribu-tion. These results of microhardness were influenced by the contact area of the indentation in zones com-posed of the bimodal structure of the YSZ coating. Keywords: Suspension plasma spraying (SPS), structure, indentation, Weibull distribution, 8YSZ coating

Surface densification of porous ZrC by a laser process

International audienceThin films of 100%-dense zirconium carbide, ZrC, on top of ca. 30%-porous ZrC are obtained by using an ytterbium-doped fibre laser under argon atmosphere. It is shown experimentally and theoretically that oxidation into zirconia or oxycarbide is completely avoided at the working temperature of at least 3420 ◦C. This type of highly refractory materials – dense at the surface and porous in the bulk – could be used in high temperature applications where both diffusion and ained by thermal carboreduction of oxides

Suspension DC plasma spraying of thick finely-structured ceramic coatings: Process manufacturing mechanisms

International audienceDue to the large volume fraction of the internal interfaces and reduced size of stacking defects, thick (from 20 to 100 μm) nano- or sub-micron structured coatings exhibit better properties than conventional micron structured ones (e.g. higher coefficients of thermal expansion, lower thermal diffusivity, higher hardness and toughness, better wear resistance, among other coating characteristics and functional properties). They could hence offer pertinent solutions to numerous emerging applications, in particular for energy production, energy saving, diffusion and environmental barriers, etc. Suspension plasma spraying (SPS) permits to manufacture such finely-structured layers and consists in mechanically injecting within the plasma flow a liquid suspension of sub-micrometric-sized or nano-sized particles through an injector of diameter of the order of one hundred micrometers. Upon penetration within the DC plasma jet, two phenomena occur sequentially: droplet fragmentation and then solvent evaporation. Particles are then processed by the plasma flow (heat and momentum transfers) prior to their impact, flattening and solidification upon the surface to be covered. Compared to plasma spraying of micrometer-sized particles (APS), SPS exhibit several major differences : i) a more pronounced sensitivity to electric are root fluctuation requiring to operate the spray gun in a relatively stable mode (take over) unless to process inhomogeneously the suspension which would results in heterogeneous coating structure; ii) a shorter spray distance (since small particles decelerate faster than bigger ones) leading to higher thermal flux transmitted from the plasma flow to the substrate (5 to 10 times higher than conventional plasma spraying); iii) an emphasized thermophoresis effect; iv) a typical cohesive structure made of the stacking of granular and flattened particles with low density of stacking defects. This paper aims at presenting recent developments carried-out on this process in terms of process optimization and coating manufacturing mechanisms

Quantification of void networks of as-sprayed and annealed nanostructured yttria-stabilized zirconia (YSZ) deposits manufactured by suspension plasma spraying

International audienceSuspension plasma spraying (SPS) allows processing a stabilized suspension of nanometer-sized feedstock particles to form thick (from 20 to 100 μm, average values) deposits. The void content and porous network of such deposits are difficult to quantify (in terms of void and size distributions, anisotropy, etc.) using conventional techniques due to their low resolution. The combination of ultra-small-angle X-ray scattering (USAXS) and helium pycnometry permits to address some of the characteristics of this void network. Deposits of yttria-partially stabilized zirconia (YSZ) were manufactured by plasma spraying a suspension made of solid sub-micrometer-sized particles (50 and 400 nm) with several sets of spray operating parameters. Results indicate that the average void size exhibits the same scale as the solid structure; i.e., nanometer sizes and multimodal size distribution which varies with spray operating parameters. About 90% of voids (by number) exhibit characteristic dimensions smaller than 40 nm. The cumulative void volume fraction of such as-sprayed deposits varies between about 13 and 20%, depending upon operating parameters. The void network architecture evolves also with annealing conditions: the void size distribution evolves toward higher void characteristic dimensions as a result of sintering of smallest voids but the cumulative void content does not decrease significantly

Micro-structure effect on radiative properties of thermal barrier ceramic coatings

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Experimental and numerical study of the influence of powder characteristics in the cold spraying of Al-based alloys for additive manufacturing using low-pressure, medium-pressure and high-pressure cold spray facilities

International audienceCold spray is continuously expanding for the repair of parts made of aluminum-based alloys, in the aircraft industry in particular. Beyond repair applications, the process is now expected to be exploited efficiently for the additive manufacturing of shaped parts. However, up to now, cold spray is limited to the achievement of rather simple shapes due to a lack of basic knowledge on coating build-up mechanisms to result in dimension-controlled deposition. The objective of the present work is to fill that gap through an experimental and modeling study of the coating build-up in cold spray for this specific application.In the experimental part of the work, Al-based coatings were deposited for a large range of particle velocity due to the use of low-pressure, medium-pressure and high-pressure cold spray facilities. Particle velocity was monitored as a function of cold spray conditions. Two different types of Al 2024 powders were tested. Coating porosity and microhardness were studied as a function of (both morphological and metallurgical) powder characteristics and spray conditions, primarily in the light of particle velocity. Various correlations could be exhibited.In the modeling part of the work, finite element (FE) simulations of particle impacts were developed, which involved particle velocity from experimental measurements. These will be used as inputs in a in-house morphological model, the first stages of which could be established successfully. First results can be considered as promising when compared to experimental microstructures and shapes